Ayaka married an older man. Her husband remarried and moved in with his son, Tatsuya, so the three of them decided to build a new home together. Ayaka thought that she had a friendly relationship with Tatsuya, who is closer in age to her husband. However, contrary to this, Tatsuya fell in love with Ayaka as a woman, not as a stepmother. Without realizing their conflicting feelings, the two of them ended up spending a week alone together...